Attenuated NER expressions of XPF and XPC associated with smoking are involved in the recurrence of bladder cancer

Abstract

The varied NER genes and smoking are two important risk factors of bladder cancer, but the mechanism of the NER protein and smoking in cancer progression, however, remains unclear. In this report, we compared the expressions of NER genes in 79 bladder cancer tissues with or without any recurrence by real-time PCR and then analyzed the varied NER genes by immunochemistry in 219 bladder cancer tissue samples. Based on the clinical data, we analyzed the clinical value of varied NER genes and smoking in 219 bladder cancers by the Kaplan-Meier method and Cox proportional hazards regression. We found the expressions of the NER gene XPF and XPC were significantly lower in bladder cancer tissues with a recurrence compared with those without a recurrence at mRNA level. Also, the patients with the XPF and XPC defect had a statistically significant lower median recurrence-free survival time than those without the XPF and XPC defect, and smoking can make this difference more remarkable. Our results suggest that XPF and XPC expression may be a potential predictive factor for bladder cancer, and smoking can not only influence the recurrence of bladder cancer as a single factor but also aggravate the results of the XPF defect and XPC defect.

Figure 1. The RNA expressions of nine NER genes in bladder cancer tissues of three subgroups.

NER genes transcript were detected by real-time quantitative RT-PCR in bladder cancers of three subgroups: Non-recurrence Group, patients who didn't have a recurrence in 2 years; Recurrence Group, patients who had a recurrence within 2 years; Dead Group, patients who were dead after the surgery within two years. The fold change was normalized against GAPDH and then all genes compared with the expressions of XPC in the Recurrence Group(+signal). *, P<0.01 compared with the.Non-recurrence Group.

Figure 2. Immunohistochemical staining of paraffin embedded bladder urothelial carcinoma.

(a)The expressions of XPF and XPA in normal bladder tissue. (b) Positive XPF expression and positive XPC expression. (c) Positive XPF expression and negative XPC expression. (d) Negative XPF expression and positive XPC expression. (e) Negative XPF expression and negative XPC expression.

Figure 3. Analysis of relative XPF and XPC mRNA levels in bladder cancer tissue with different smoking status.

The expressions of XPF and XPC in 79 the bladder cancer of 4 smoking subgroups. The coarse solid line represents the mean CT value and the error bars represents the standard error.

Figure 4. Expression of XPF and XPC bladder cancer recurrence.

Kaplan-Meier Curves using log rank tests for the recurrence of bladder cancer in patients. (a) The recurrence of bladder cancer in patients with XPF(−) and XPF(+); (b) The recurrence of bladder cancer in patients with XPC(−) and XPC(+); (c) The recurrence of bladder cancer in patients with XPF (−) combined with XPC(−) and XPF(+) combined with XPC(+), simultaneity; (d) The recurrence of bladder cancer in patients with never smoked and ever smoked. Cum, cumulative.

Figure 5. The smoking status and bladder cancer recurrence.

Kaplan-Meier Curves using log rank tests for the recurrence of bladder cancer in patients. (a) The recurrence of bladder cancer in XPF(−) group with different status of smoking (never smoked, <20 pack-years, 20-50 pack-years and>50 pack-years); (b) The recurrence of bladder cancer in XPC(−) group with different status of smoking; (c) The recurrence of bladder cancer in XPF(+) group with different status of smoking; (d) The recurrence of bladder cancer in XPC(+) group with different status of smoking; (e) The recurrence of bladder cancer in patients of XPF(−) with never smoked and XPF(−) with smoked more than 50 pack-years;(f) The recurrence of bladder cancer in patients of XPC(−) with never smoked and XPC(−) with smoked more than 50 pack-years;(g) The recurrence of bladder cancer in patients of XPF(+) with never smoked and XPF(+) with smoked more than 50 pack-years; (h) The recurrence of bladder cancer in patients of XPC(+) with never smoked and XPC(+) with smoked more than 50 pack-years.